Microtubules and Motor Proteins for Synthetic Beating Cilia*

In nature, many vital processes rely on fluid flow based transport of cargo in order to overcome the time constraint of diffusive transport. The most common transport motif involves flows driven by cilia or flagella, from removal of pollutants in the trachea to the movement of microscopic organisms in viscous fluid environments. Cilia are microscopic hair-like structures, flexible membrane extensions of the cell that present a rhythmic waving or beating motion. Each cilium comprises microtubule-doublet bundles held together by several proteins.
We aim to develop synthetic ciliated systems able to propel themselves or to move fluids across a fixed surface. By assembling a simple system made of just a few building blocks adapted from natural cilia, namely microtubules and motor proteins, the issue that we address is: how simple is the simplest system that is able to beat?
By using the motor protein kinesin-1 we synthesized microtubules structures powered by ATP hydrolysis that are able to generate spontaneous oscillations. By binding them to a surface using a suitable anchor system, we can observe the microtubules-motor protein system oscillations in a manner that closely mimics ciliary movement.